The deployment of IPv6 has dramatically reduced address pressure in IPv4. However, a 128-bit IPv6 address is not so easy to remember as an IPv4 address, and domain names will be put into more extensive applications in IPv6. Currently, there are two methods for configuring domain name information in IPv6: (1) to manually add the mapping relation between an address and a domain name to a DNS server; (2) to automatically update a domain name using FQDN (fully qualified domain name) options in the DHCP protocol (dynamic host configuration protocol). Method (1) needs manual intervention and is thus hardly competent for a large number of hosts. Method (2) is merely applicable to hosts that configure addresses using DHCP.
There are two kinds of address configuration manners in IPv6, namely stateful address configuration and stateless address configuration. The stateful address configuration manner means configuration of address and other information by the DHCP protocol. Similar to IPv4, this method needs a DHCP server from which the host obtains information on address configuration in client/server mode.
The stateless address auto-configuration is a characteristic address configuration manner for IPv6. In this manner, the network interface requiring address configuration obtains a link local address using neighbor discovery mechanism first, and after obtaining the link local address, the network interface sends a router solicitation (hereinafter referred to as RS) message to a full router multicast address. The local router transfers the prefix of one or more global addresses to the host by router advertisement (hereinafter referred to as RA) message. Finally, the host combines the obtained address prefix and the interface identifier to get a global address. The router may also periodically send a RA message, and the host, upon acquisition of the message, configures the interface's global address in accordance with the address prefix.
The stateless address configuration method used in IPv6 is a distinct advantage of IPv6, which enables the host device to obtain the IPv6 address without manual configuration or DHCP server maintenance.
However, there is so far no method for automatically updating DNS for a host that configures addresses using a stateless address configuration method. The existing IPv6 router advertisement based DNS auto-configuration is an obsolete draft and has following deficiencies not to be ignored:
On the one hand, since this method does not specify the matching relation between domain name suffix information and address prefix, if the router has issued a plurality of address prefixes, then the host cannot correctly identify the matching relation;
On the other hand, it is the host that automatically updates a DNS domain name according to this method, which will cause security pitfalls. Even if security guarantee is implemented using the DNSsec method, corresponding authentication information needs to be installed on each host, which will make the DNS updating very complicated.